As described in Japanese Patent JPA 2006-153746, in a conventional exhaust gas analyzing apparatus, an introduction path for introducing exhaust gas discharged from an engine installed in a test chamber is equipped with a dust filter for removing dusts and soot in the exhaust gas. The dust filter is clogged with adhered dusts and soot and thus, needs to be replaced periodically (for example, every eight hours).
However, since the dust filter is often arranged in the test chamber, a user need to enter the test chamber to replace the dust filter. The test chamber is under high temperatures due to activation of the engine of the vehicle or the like, and moreover, the dust filter is arranged in the vicinity of the engine or the exhaust pipe under high temperatures. Accordingly, the user has to replace the dust filter in a high-temperature environment and bear an enormous load. Moreover, the operation of replacing the dust filter is performed in the vicinity of the engine or the exhaust pipe under high temperatures, which is dangerous. The operation of replacing the dust filter can be performed after the engine or the exhaust pipe is cooled. In this case, however, it takes a long time to start next measurement of the exhaust gas.
In recent years, continuous measurement (for example, 24-hour continuous measurement and 48-hour continuous measurement) of the engine of the vehicles and the like has been demanded. However, as described above, continuous measurement needs to be stopped to replace the dust filter. Therefore, it is difficult to make desired continuous measurement.